Piping Material Specification 12 PD0H02, SDR-11, High Density Polyethylene (HDPE), Utility (Underground)
standard by Process Industry Practices, 12/01/2003

Piping Material Specification 12 PD0H02, SDR-11, High Density Polyethylene (HDPE), Utility (Underground [Complete Revision]
standard by Process Industry Practices, 10/01/2012